1) Field of the Invention
The present invention relates to a charging communication-adaptor for a mobile device having functions for charging the mobile device and establishing communication between the mobile device and an external device.
2) Description of the Related Art
Various types of adaptors for the mobile devices are known. Some of the adaptors, charging adaptors, have a function to only recharge the battery of the mobile devices. Other adaptors, communication adaptors, have a function to only establish communication between the mobile device and an external device. Still other adaptors, charging communication-adaptors, have functions of both, to recharge the battery of the mobile devices and to establish the communication between the mobile device and the external device. The external device may be a personal computer (PC) or a server.
The charging communication-adaptors broadly have two types: direct-contact adaptors and wireless adaptors. Japanese Patent Application Laid Open No. H09-294108 discloses a wireless charging communication-adaptor that performs communication with the mobile device using infrared light. The charging communication-adaptor is connected to an external device via a cable.
The direct-contact charging communication-adaptor has communication terminals, corresponding to communication terminals of the mobile-device, and charging terminals, corresponding to charging terminals of the mobile device. When the mobile device is attached to the charging communication-adaptor, the charging terminals of the mobile device make an electrical contact with the charging terminals of the charging communication-adaptor and the communication terminals of the mobile device make an electrical contact with the communication terminals of the charging communication-adaptor. As shown in FIG. 14, the charging communication-adaptor is connected to an external device via communications means, such as USB or RS-232C cable, to establish a communication between the mobile device and the external device.
In the direct-contact charging communication-adaptor, if the mobile device is placed on the charging communication-adaptor in such a manner that the communication terminals of the mobile device make an electrical contact with the communication terminals of the charging communication-adaptor before the charging terminals of the mobile device make an electrical contact with the charging terminals of the charging communication-adaptor, an unstable voltage is applied from the external device to the charging communication-adaptor or the mobile device and there occurs a communication error.